1. Field of the Invention
The present invention relates to a laser processing method of applying a laser beam to the inside of a thin platelike workpiece such as a semiconductor wafer from the back side thereof, thereby performing laser processing to the workpiece.
2. Description of the Related Art
In a semiconductor device fabrication process, a plurality of devices having electronic circuits are formed on the front side of a semiconductor wafer in a plurality of regions partitioned by a plurality of crossing division lines (process lines). The semiconductor wafer thus having the plural devices is divided along the division lines to thereby obtain a plurality of individual semiconductor chips respectively corresponding to the plural devices. As a method of dividing a workpiece such as a semiconductor wafer, there is a method including the steps of applying a laser beam having a transmission wavelength to the workpiece along each division line in the condition where the focal point of the laser beam is set inside the workpiece, thereby forming a modified layer inside the workpiece along each division line, and next applying an external force to the workpiece to divide the workpiece from the each modified layer as a break start point (see Japanese Patent No. 3408805, for example).